Among the so-far known processes for producing the above-mentioned optically active homophenylalanine derivative (IV), there is a process using a biocatalyst such as an enzyme, and the process employing the so-called asymmetric synthesis without using any biocatalyst such as an enzyme.
As the above-mentioned process using a biocatalyst, Japanese Kokai Publication Hei-01-79134, for instance, discloses a process involving asymmetric decomposition of a corresponding hydantoin with hydantoinase, and Japanese Kokai Publication Hei-02-31694 discloses a process comprising asymmetrically hydrolyzing a corresponding aminonitrile with nitrile hydrolase. These processes, however, require the use of a toxic hydrocyanic acid compound in raw material synthesis.
U.S. Pat. No. 5,316,943 discloses a process comprising trans-amination of a corresponding keto acid with transaminase and, in the Journal of Organic Chemistry, vol. 55, page 5567 (1990), there is disclosed a process comprising reductively aminating a corresponding keto acid using phenylalanine dehydrogenase. These processes, however, require the use of an expensive keto acid as a material.
In the Journal of the American Chemical Society, vol. 112, page 945 (1990), there is disclosed a process which comprises asymmetrically hydrolyzing a corresponding ester using an enzyme and, in the Bulletin of the Chemical Society of Japan, vol. 55, page 918 (1982), there is disclosed a process comprising asymmetrically hydrolyzing a corresponding acetyl derivative using acylase. These processes, however, are processes for racemic resolution, hence, theoretically, the desired compounds can be obtained only in half amounts relative to the total amounts of starting racemates. Another disadvantage lies, for example, in the complexity of operational procedure.
As the above-mentioned process comprising asymmetric synthesis, there may be mentioned the process in which a chloroacetyl containing compound is reduced with an asymmetric boron complex followed by rearrangement (the Journal of the American Chemical Society, vol. 114, page 1906 (1992)), the process comprising hydrogenating a 4-phenyl-2-aminocrotonic acid derivative with an asymmetric rhodium complex (the Journal of Organic Chemistry, vol. 52, page 5142 (1987)) and the process comprising reacting an optically active glycine derivative with phenylpropyl bromide (the Journal of the American Chemical Society, vol. 108, page 1103 (1986)), among others. These processes for asymmetric synthesis, however, require the use of an expensive catalyst or an organometallic compound difficult to handle.
As the above-mentioned process comprising optical resolution of the optically active homophenylalanine derivative (IV), there may be mentioned, for example, the process comprising resolving a corresponding N-formyl derivative using phenethylamine (Japanese Kokai Publication Sho-63-63646), the process comprising resolving a corresponding methyl ester using mandelic acid (Japanese Kokai Publication Sho-63-145256) and the process comprising resolving a corresponding N-acetyl compound using brucine (the Journal of Biological Chemistry, vol. 122, page 348 (1937 to 1938)), among others. Theoretically, however, these processes can give the desired compounds only in half of the total amounts of starting racemic mixture and are also disadvantageous in that their operational procedures are complicated.
The so-far known processes thus cannot necessarily be said to be satisfactory.
In view of the foregoing, it is an object of the present invention to provide an economically advantageous and efficient process for producing the above-mentioned optically active homophenylalanine derivative (IV), and an intermediate therefor and a process for producing it.